Olfactory glomeruli are the common functional elements in vertebrate and invertebrate neural pathways involved in integrating sensory information about complex odor mixtures. Previous studies have shown that insects can be excellent models for studying the functional role of glomeruli. One of the most studied involves the sex pheromone-processing pathways in the male-specific macroglomerular complex (MGC) of the antennal lobe of male moths. Olfactory glomeruli in the MGC are critically involved in the spatial organization of sensory axons for specific pheromone components and their interactions with specific local interneurons and projection neurons that integrate key aspects of odor quality, quantity, and intermittency. The objectives of the present proposal are to test hypotheses about the interactions of sensory afferents and central neuron types in the olfactory glomeruli, utilizing the technique of transplantation of antennal imaginal disks between males and females of two heliothine moths, the tobacco budworm, Heliothis virescens, and the corn earworm, Helicoverpa zea. These two insect species have been the subject of extensive studies on pheromone blend discrimination, and electrophysiological/anatomical studies of neural pathways involved in processing the pheromone signal. The antennal transplant procedure will allow construction of males and females with unique antennal and behavioral response phenotypes to test a model for glomerular organization and behavioral discrimination of odor quality. These inter-species antennal transplants represent a new experimental paradigm for studying basic aspects of the structural and functional role of glomeruli in olfactory discrimination.